1. Field of the Invention
The present invention relates to an active device and a fabricating method thereof.
2. Description of Related Art
A thin film transistor liquid crystal display (TFT LCD) panel mainly consists of an active device array structure, a color filter array structure and a liquid crystal layer. The active device array structure includes multiple active devices arranged in array, i.e. an array of thin film transistors (TFTs), and a pixel electrode disposed in correspondence with each TFT. The TFT includes a gate, a channel, a drain and a source. The TFT serves as a switch element for a liquid crystal display unit.
An oxide semiconductor is a common material for fabricating the TFT. When the oxide semiconductor TFT is used as the switch element for the liquid crystal display unit, because the channel of the oxide semiconductor material has a high light transmittance, there has been an alignment difficulty in stacking other materials in subsequent processes. Although increasing the thickness of the channel of the oxide semiconductor material may decrease its light transmittance, it causes a threshold voltage shift of the channel. Therefore, when the oxide semiconductor TFT is used as the switch element, it is desired to achieve high alignment accuracy in the process without increasing the thickness of the oxide semiconductor.